Deep Space Nine aired in January 1993, Babylon 5 pilot in February '93 but the series didn't come along until 1994. The story arc leading to DS9 was built up in ST TNG. So I don't think DS9 ripped off B5 as it was in development prior to B5. Both are set on space stations which is why I think DS9 often gets accused of ripping off B5. B5 has dated badly now with the (then) TV CGI which DS9 & Voyager resisted going full CG. B5 does now look a bit like a video game of the era. Ironically, the guy who did the original B5 effects went on to Voyager and the episode 'Timeless' raised the bar for TV CGI with the ship crashing onto a glacier.
